Mozilla Foundation Security Advisory 2008-07

Possible information disclosure in BMP decoder

Announced

February 19, 2008

Reporter

Gynvael Coldwind // Vexillium

Impact

Moderate

Products

Firefox, SeaMonkey

Fixed in

Firefox 2.0.0.12

SeaMonkey 1.1.8

Description

Security researcher Gynvael Coldwind of Vexillium
(crediting help from udevd and porneL)
demonstrated that BMP images
could be used to reveal small chunks of uninitialized memory
that might contain sensitive data from other pages or other
programs, and that this data could be extracted from the
image using methods associated with the <canvas>
feature.

Because this flaw also affected products from other vendors disclosure
was delayed until they could release a fix.

Update: Thunderbird was incorrectly listed as affected by this
vulnerability. The maliciously formed BMP images would contain
noise influenced by uninitialized memory as in Firefox, but Thunderbird
lacks the <canvas> feature necessary for an attacker
to extract the data from the image.

Workaround

Disable JavaScript until a version containing these fixes can be
installed.